Problem with my collimating lens

[fabio00]

Hi everyone,
i repaired a green laser from a laser projector but i have some problems with the collimating lens i changed. I have a very big spot and to focus the laser beam I have to move the lens to a large distance,not compatible with the lens as you can see in photo.What's wrong with the collimating lens i choosed?How can i choose the right lens?Thanks for your help

 

[RedCowboy]

Your new lens is likely a different Focal Length than your old lens, try to find a better match.

 

[Ricker]

I would try a G8. Can't promise it will work but a good place to start.

 

[fabio00]

ok guys,thank you so much

 

[paul1598419]

Optics are not that difficult. The focal length of your lens will need to be that distance from the emitter face of your diode. You are actually making a beam by focusing the emitter as you would a camera image on your digital CCD or CMOS sensor. Get it?

 

[Unown (WILD)]

This may be a returning banned member